Apparatus for testing dielectric strength of fluid



Sept. 12, 1933. D, B. CLARK 1,926,084

APPARATUS FOR TESTING DIELECTR'IC'ISTRENGTH 0F FLUID Filed Dec. 20, 1926 J'i 1. 4 5- Ivi .2..

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if ,M QQJM atkouuap Patented Sept. 12, 1933 vLentini APPARATUS Fon 'nismo nmLEormc smi-:Nora or FLUm David B. Clark, Oxford, Mass., assigner to Goulds Pumps, Ino., Seneca Falls, N. Y., a corporation ol' New York Application 20, 1926 Serial No. 155,969

l Gleim.

My invention is concerned with e device for testing the dielectric properties of oil such es is used in electricol apparatus for the purpose oi providing insuletion.

The customary method of testing the dielectric properties or en insulsiting` oil is to segregate e comple thereof in en open vessel und to note whether or not o sperk posses between two electrodes which entend into the oil sample und which ere spaced s. predetermined distance eport ond subjected to e. predetermined potentiel difterence.

This inethod oi -testing the insulating qualities oil the oil hers several disadvantages, ninong which nre the feet that only e 'sample of the oil is tested und the iect thet the oil, in the testing vessel, is suhiecd to exposure to oir end muy es e. iult obsorio moisture ondeir which modify its dielectric properties.

lit is the object oi my invention to produce e testing device by which en operetor een deter= urine the dielectric strength of en entire uuentity oi oil es distinguished from that oi e mere seniple thereof. A further object of my invention is to produce on oil testing device in which the oil being tested will not be subjected to exposure to nir, moisture, or other substances which would sheet its dielectric strength. p

l accomplish the above objects by providing e closed vessel having inlet and outlet openings end adopted to have e quentity of oil now through it. In this vessel are located e pair or electrodes which are spaced s predetermined distance eport and which are subjected to e predetermined potentiel difference. The vessel hes e transparent woll or other provisions whereby the passage of s, spark between the electrodes muy be observed. Desirably, the vessel in which the oil is tested is orrenged to be connected in o pipe system through which the insulating oil posses, and ineens are provided whereby ell the oil or only e pei-t oi the oil passing through the pipe 'system moy olso poss through the testing` spperetus.

The occompenying drawing illustretes my invention: Fig. l is e. fregmentol vertical section on the line l-l of Fig. 2 illustrating the construction of the testing device; Fig. 2 is e. side elevation of the testing device in partiel section; and Fig. 3 is a horizontal section through the testing device on the line 3 3 o! Fig. l.

In the drawing, I have illustrated my testing device es connected in a pipe v15, the testing device being adapted to test the dielectric strength of oil passing through such pipe.

558. By rotating the hand wheel 55, the gloss 56 lower plete of insuleting materiel 'l0 is mounted My testing device embodies e. frame 50 adapted to be inserted in the pipe 45 ond provided with on oil passage 51 in line with such pipe. ln the frame 50, near each end oi the oil psssege l, I mount three-wey vulves 52 by means of which @il some or all of the oil flowing through the pipe may be diverted through the testing ineens.

Projecting laterally neer the top of the ironie is o. hollow erm 541. to the underside of which is emxe'd d fienged cep 55 adopted to receive the @5 upper end of o. hollow cylinder 56 formed oi gless or some other transparent nieteriel. second cop '57, similar to the csp 55, receives the lower end of the cylinder 56 und is provided centrally with e, downwardly extending hollow shank 55 slidoble within e pecking dong@ 55 in e. second hollow erm 6o which projects laterally neer the bottom of the ironie 50. Preferably, gaskets 5i' nre provided between the ends oi the cylinder 55 end the cops 55 and 57. g5

Suitable means is provided for clamping the hollow cylinder 55 between the cops 55 ond 57. Such ineens rney conveniently tene the forni oi e hund wheel 55, the stem 56 of which projects through e 'glendt' und is screw-threadedly sup- @29 ported from the erin 65. At its inner end, the stem 66 is provided with e. heed 65 adopted to be received in o Tr-slot in the lower endoi the shank muy be securedly clamped between the oeps 55 end 57. f v

The hollow shenlr 58 of the copv 57 communicotes-with the hollow erm 50 ond e. passere is provided through the ccp 55 to the interior oiV n the hollow erin 5d. Thus when the vulves 52 ore properly adjusted, oil muy ilow through the erm 50 und the shank 58 into the cylinder end thence beck to the pipe through the hollow erm 54.

The yoil-testing ineens is located within the hollow cylinder 55 und comprises two pletes 'lo end '71 oz? insulating materiel which are support-1 ed in vertically spaced relation on three legs "l2 by ineens of nuts 73. Neer the center of the en electrode in the form oi' e, plug 75 provided with e. screw-threaded stern 76 which entends through the plete '70 sind on the underside thereof is provided with s. nut 77 by ineens oi which the plug 'T5 may be secured to the plete. A simin ler plug 78 heving' o, thresded stem 79 end nut 80 is mounted in the plete 'll ebove the plug 15. The adjacent feces of the plugs und 'i8 sire preferably plane und perellel. One of the plugs, here shown es the plug 78, is provided with en axial hole so that oil in passing through cgi-f ico , A inder 58 may between the two plugs 75 and 78 and upward through such axial hole.

ward to forma contact iinger 82 adapted to engage a contact 83 mounted in the wall ofthe cylinder 56. A similar contact linger 84 serves to connect the plug 78 with a second contact 85 alsojmountedin the wall of the cylinder 56 and f conveniently located diametrically opposite to the contact 83. The contacts 83 and 84 are conveniently provided with screw-threaded shanks which extend through the wall ,of the cylinder 56 and on the outside thereof are provided with washers 86 and nuts 87 for the'purpose of holding the contacts in place.

In electrical contact with the shanks of the contacts 83 and 84 are two contact fingers 90 and 91 respectively which are conveniently supported from a strip 92 of insulating material mounted'on the frame 50. .The Vfingers 90 and 91 are connected to the secondary of a transformer 93 in order that a potential difference may be created betweenthe electrodes and 78. Preferably, the fingers` and 91 are heldin contact with the shanks of the contacts 83 and 84 by their own elasticity in order that they may not interfere with the ready removal of the cylinder 56.

In the operation of my device, the plates 70 and 71 are adjusted so that the electrodes 75 and 78 are a predetermined distance apart, such I distance being great enough so that the oil between the electrodes 75 and 78 will not break down under the potential difference existing between the electrodes when the oll is of the desired purity. The three-way valves 52 are arranged to pass through the tester either all or a part of the oil flowing through the pipe 45.

' The operation of the device will be evident.

With oil passing through the testing device, and with a predetermined potential difference imposed on the electrodes 75 and 78 by the transformer 93, the operator observesthe electrodes through the transparent side wall 56 of the testing vessel. So long as no spark between the electrodes, the operator knows that the oil ilowing through the testing apparatus is of satisfactory dielectric strength. When a spark passes between the electrodes, however, it is evidence that the oil in the testing device is of insuilicient dielectric strength, and the operator may take whatever steps may be desired -or necessary.

If desired, I may include in the primary circuit ofthe transformer 93 an alternating-current relay 112. So long as no spark passes between the electrodes 75 and 78, the secondary circuit of the transformer is open, and no current flows in the primary circuit. The relay 112is therefore deenergized. When the oil between the electrodes breaks down, however, current ows in both the secondary and primary circuits of thev transformer 93, and the relay 112 is energized. The relay 112 may be used for vvarious purposes, some of which are disclosed in my co-pendinu application Serial No. 379,596 led July 19, 1929.

I claim as my inventionz- An oil-testing device, comprising a casing, a support therefor, end closures for said casing, one of said end closures being provided with a shankA mounted for longitudinal sliding move- -ment in said support, said support having a 

